Telephone system.



No. 878,151. PATENTED FEB. 4, 1908 A. L. PAROELLE, DECD.. w. A. PARGELLE, ADMINISTRATOR.

TELEPHONE vSYSTEM.

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UNITED STATES PATENT OFFICE.

' ALBERT'L. FAROELLE, OF BOSTON, MASSACHUSETTS; WALTER A. PAROELLE ADMINISTRATOR OF ALBERT L. PAROELLE, DECEASED.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Feb. 4, 1908.

T 0 all whom it may concern:

Be it known that I, ALBERT L. PARCELLE, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Telephone Systerns, of which the following is a specification.

This invention has relation to telephone systems, and has for its object, generally speaking,-to provide improvements therein by which a more perfect and sharper articulation is secured.

In Letters Patent No. 772,630, granted to me on the 18th day of October, 1904, I have illustrated and described a telephone system in which two branch circuits, each connected in series with a separate microphone, are provided with primary coils (there being a separate core for each primary) acting upon a single or common secondary coil or winding in the receiver circuit. I have found that the employment of two microphones connected to a single diaphragm, necessarily requires a complication of parts from which trouble may be fairly expected to ensue. The forward or inward movement of the diaphragm, under pressure, is longer than the outward or rearward movement, and it is diiiicult to adjust the apparatus so that the two'microphones are equal in effect.

Accordingly the present invention has further for its object the provision of a telephone system in which a single microphone will aflect' or control independent primary coils and cores which have in common a secondary coil in the receiver circuit.

As will be subsequently explained in detail, the local circuit at the transmitter station comprises a plurality of branch circuits receiving their current from a common battery.

The primary coils are so wound and connected in their respective branch circuits, that they are energized alternately by the forward and backward movement of the diaphragm; that is to say, while the current is rising in one primary coil, it is fallingoff or waning in the other primary coil, so that the magnetic lines from the two cores act in conjunction on the secondary coil to produce a double or increased action. Thus every movement of the diaphragm produces a double or increased effect.

Referring to the drawings,Figure 1 illustrates diagrammatically a simple form of the invention. Fig. 2 represents the same form of the invention with the addition of a variable resistance in what I may term the second branch of the local circuit, the first branch including the microphone. Fig. 3 represents another embodiment of the invention in which there are three branch circuits. Fig. 4 illustrates conventionally one of the induction coils in which a single secondary coil is wound about two primaries and their separate cores.

Referring to the drawings, and particularly to Fig. 1, the microphone is indicated conventionally at a and the diaphragm at I). These are arranged in a local circuit which comprises two branch circuits 0 and (Z which have in common the battery 6 and the conductor c. The first branch circuit 0 and the second branch cl of the local circuit are provided with the primary coils or windings c d with their respective cores 0 and d (Fig. 4), said cores and coils acting upon a secondary coil or windingf in the receiver circuit] (see Fig. 1). In the second branch circuit, there is a condenser (1 These two branch circuits are controlled by the diaphragm t and microphone a and they both receive their current from the same battery 6. The current, in flowing from the battery 6, divides at a point a, a part passing through the branch circuit a and the other passing into the branch circuit (1. When the conductivity of the microphone a is increased by the movement of the diaphragm forward, there is a rush of current in the branch. circuit 0 and a ractical cessation or diminution of current in the branch circuit at, the condenser (:1 discharging so that the current will flow backwardly through the coil or winding (1. When the'conductivity of the microphone is diminishedby a movement of the diaphragm outward or backward, the flow of current through the branchc will cease or drop off, and current will again flow through the branch d towards the condenser (1 The result of these actions, which are repeated each time the diaphragm vibrates, is the induc tion in the receiver circuit f of electrical impulses of greater current strength than it is possible to obtain with a single primary coil in a transmitter circuit, said impulses being sharpened by the charge and discharge of the condenser.

In Fig. 2, I have shown substantially the same arrangement of branch circuits except that the condenser 61 is omitted, and I have utilized a variable resistance (1 in the branch circuit d to balance the resistance of the microphone in the branch 0. In this case, when the local circuit is closed as ordinarily by removing the receiver from the hook, a portion of the current flows through the branch circuit d and a portion through the branch circuit 0. I/Vhen the diaphragm moves forward or inward, a greater amount of current flows through the circuit 0 and a smaller amount through the circuit d. This causes the lines of force of the core of the coil (1 to fall off coincidently with the increase of the lines of force of the core of the coil 1. When the diaphragm moves backward, a reverse action takes place with practically the same results as before stated. There are several ways in which these connections may be made so that two branch circuits, controlled by the microphone, will affect a common secondary in the receiver circuit. In any case, it is preferable that the battery should be adapted to the resistance of the entire local circuit and that the several branch circuits should be approximately balanced.

In a telephone transmitter, only a limited amount of current can pass through the microphone, the movement of the diaphragm causing the amount to vary between the maximum and minimum. According to my invention the same variations of current take place in what may be termed the second or outside circuits .(as (Z in Fig. 1) as in the microphone circuit. As this outside circuit is controlled or governed by the diaphragm acting on the microphone, the variations will be the same, and, as this extra current acts upon the same secondary wmdmg, double the energy Wlll be thrown upon the line.

' As illustrating still another embodiment of the invention, I have shown another system in Fig. 3. Here three primary windings, each having its own core, are employed, they being placed respectively in the circuits 0 d and g. All three of these circuits are controlled by the diaphragm and microphone. The circuit 9 is provided with a variable resistance indicated conventionally at 9 As each of these branch circuits d and g is in multiple with the circuit 0, neither has any influence on the microphone, their, action being entirely on the secondary f of the induction coil.

. What I claim is 1. In a telephone system, a local transmitter circuit, comprising branch circuits arranged in multiple, only one having therein a microphone, and each of said circuits having a primary winding with a separate core; and a receiver circuit having a secondary winding common to said primary windings and cores.

2. In atelephone system, a source of power, a transmitter circuit comprising two or'more branch circuits connected in multiple with each other and with said source of power, one of said branch circuits including a microphone, and all of said branch circuits including primary windings with separate cores; and a receiver circuit having a secondary winding common to said primary windings and cores.

3. An electrical apparatus comprising a source of power, branch circuits in multiple with relation to each other but connected with said source of power; a primary coil in each of said branch circuits with a separate core; a secondary winding common to all of said primary coils and cores; and means in one of said branch circuits for varying the current flowing therethrough.

4. In a telephone system, the combination with a transmitter circuit comprising a plurality of conductors arranged in parallel, a transmitter in one of the conductors and a condenser in another of said conductors, of a receiving circuit, and an induction coil having a primary winding in both the transmit ter and condenser conductors and a secondar T windin coo eratin with the rimarv l) O u windings, and being included in the receiving circuit.

In testimony whereof I have aflixed my signature, in presence of two witnesses.

' ALBERT L. PAROELLE.

I/Vitnesses:

MARoUs B. MAY, A. L. FoLsoM. 

